The invention relates to a closure membrane for use with a compressible container (squeezable bottle).
The invention further relates to a closure membrane with a closure head and a retaining border, the closure head being connected to the retaining border via a connecting wall adjoining the outer border, with the entire arrangement being of essentially cup-shaped design, and, furthermore, the closure head preferably being of a thickness which increases outwards from the center.
Such closure membranes have already been disclosed in a large number of configurations. You are referred, for example, to EP-A-545 678, also to EP-B-046 464, EP-A-442 379 and U.S. Pat. No. 2,175,052 and, additionally, to German Patent Application 19613130.8, which is not a prior publication. The disclosure of the last-mentioned patent application is included in full in the disclosure of the present application, also for the purpose of incorporating features of said patent application in claims of the present application.
Such a closure membrane is not yet regarded as optimum in all respects as far as its closure behavior is concerned. This is also put down to the fact that, in particular depending on the specific installation conditions, forces acting on the connecting wall have an undesirable effect on the closure head.
Taking said prior art as a basis, the invention is concerned with the technical problem of specifying an improved closure membrane. This technical problem is solved with the features of claims 1 and 7, respectively. The dependent claims are directed to preferred embodiments of the present invention.
The closure membrane for a packaging container according to the present invention comprises a closure head wherein at least one head plate ring is formed on the closure head. Preferably the head plate ring is formed around its border. Furthermore, it preferably extends essentially perpendicular with respect to the plane of the closure head. This head plate ring preferably has the function of a strengthening ring. The closure membrane according to the present invention further comprises a retaining border and a connecting wall connecting the closure head and the retaining border wherein the connecting wall comprises a first part and a second part. The first part forms a tubular member whereas the second part forms an annular member. Upon pressure to the inner surface of the closure membrane the tubular member and the annular member are deformed in such a way that the closure head is moved outwardly with respect to the retaining border. Preferably the second part of the connecting wall forms a hinge spring which is preferably designed as a frustoconical washer which will also be named hereunder a cup-spring ring.
In a further embodiment of the invention the connecting wall is attached to the closure head via a connecting web, which projects radially inwards from the connecting wall and is of a lesser thickness than the border region of the closure head. According to the invention, the region where the closure head is connected to the connecting wall tapers, in cross-section, with respect to the (border-side) thickness of the closure head. Nevertheless, the resulting radially inwardly projecting connecting web is closed all the way round, this further maintaining the closed state of the closure membrane. It has advantageously been shown that, as a result, the movement of the closure head is largely isolated from the movements and the forces to which the connecting wall is subjected or which act on the connecting wall.
The connecting web acts as a hinge, with little or no flexural rigidity. Preferably the thickness range is 0.2 mm to 0.35 mm, especially 0.25 mm. The connecting wall is preferably at least 50% thicker than the connecting web. A preferred thickness range is 0.3 mm to 0.6 mm, especially 0.4 mm. This construction has the advantage that hinging occurs preferentially at the connecting web. It further allows easy molding of the closure membrane. In a further configuration, it is also provided that the connecting web adjoins the closure head approximately centrally, as seen in the vertical direction. The connecting web may advantageously adjoin the closure head eccentrically, as seen in the vertical direction. It is also possible for the connecting wall to extend beyond the connecting web such that a peripheral groove is formed with the border edge of the closure head. This may also be advantageous as regards supporting the border edge on a top closure part or a hinge mechanism of the closure head. It is also advantageous if the connecting wall and the connecting web are connected to the closure head so as to produce, in cross-section, two mutually opposite, peripheral grooves, between the connecting wall and the closure head, which are separated by the connecting web. In a further detail, it may also be provided, in relation to a closure into which such a closure membrane is inserted, that, in the non-actuated installed state, the closure membrane has a bottom retaining border and a top, essentially concave closure head, the closure head and the retaining border, furthermore, being connected to one another by said connecting wall. It is also preferred for the installed state of the closure membrane to be achieved by turning the closure membrane inside out after it has been produced by injection molding. This produces favorable force effects. In particular, on the one hand, the concave closure head is advantageously prestressed into its closed state by radially acting forces of the inside-out connecting wall. On the other hand, however, rapid opening, in particular for ventilating purposes, during sucking back, should also be noted. Furthermore, starting from a border-side attachment to the closure head, the connecting wall may preferably continue into a constriction beneath a projection area of the closure head, this observation once again being based on the installed state. As is explained in more detail below, this is achieved, in particular, in that, in the production state (injection-molded state), the connecting wall extends essentially cylindrically, starting from the closure head. Depending on the desired properties of the closure membrane, however, there may also be a variation here in terms of a conical configuration. Continuation into a constriction beneath the projection area of the closure head produces something of a goblet-like configuration of the closure membrane as a whole in this region. Furthermore, there are also applications in which, even in the installed state, the connecting wall adjoins the bottom of the closure head in an essentially cylindrically extending manner, in particular when the above-mentioned operation of turning the closure membrane inside out after production is not carried out.
Specifically, it is advantageous, in particular with respect to the above-described inside-out, installed state, if, as has already been mentioned, the border side of the closure head is of a greater thickness than the boundary wall. The abovedescribed connecting web, in particular, also has an advantageous effect here. The closure head may taper inwards continuously, starting from its border region. The boundary wall is attached to a top region of the border edge, as seen in cross-section, of the closure head of the closure membranexe2x80x94this observation once again being based on the installed statexe2x80x94and the boundary wall grips over a bottom, free border region of the boundary edge of the closure head. As a result of the above-described, advantageously set compressive forces directed towards a center point of the closure head, this being achieved by a certain enforced widening of the elastic material of the closure membrane, in particular of the connecting wall, a radially inwardly directed force is thus exerted on the border edge of the closure head, essentially over the entire circumference. These forces are also absorbed extremely favorably as a result of the closure head extending in a dome-shaped manner. At the same time, as a result of the above-described attachment via a connecting web, a little-desired moment is transmitted to the closure head only to a slight extent, if at all. As a result of the prevailing radial forces and the resulting prestressing in the closure membrane and, in particular, in the closure head of the closure membrane, further advantageous properties are achieved during actuation of the closure membrane. The resulting prestressing in the dome-shaped structure of the closure membrane, on the one hand, ensures a high sealing force and, on the other hand, when the dome-shaped structure is disrupted (dispensing operation or sucking back), breaking out also takes place straight away in response to relatively low force exertion. In a conventional dispensing operation, the radial opening slits preferably provided in the closure head open, above a certain pressure, reliably and almost abruptly. As a dispensing operation is completed, and the squeezable bottle on which the closure, for example, is fitted returns into its original position, first of all the closure head is drawn into the initial, concave state, in a conventional manner, and then it opens out downwards with sucking back of air, which, despite the above-described stressing prevailing in the closure head, does not require a great amount of force or negative pressure, but rather only a relatively small amount thereof. In a further advantageous configuration, it is also provided that, in the injection-molded state, the connecting wall runs essentially cylindrically. However, as has already been mentioned, the above-described prestressing to which the closure head is subjected in the inside-out state of the closure membrane, or a funnel formation, may also be influenced and varied by a change in the angle in the connecting wall (as seen in cross-section). The connecting wall merges into a peripheral reinforcement region, and a fastening ring is attached to the reinforcement ring. The reinforcement ring has proven to be advantageous, in particular, with respect to the closure membrane moving out telescopically in the event of pressure build-up, as is described in more detail below. The fastening ring serves for retaining the closure membrane in the closure. In a further preferred detail, it is provided that the fastening ring is connected to the reinforcement ring via an attachment wall which, in cross-section, extends at an angle to the connecting wall.
In relation to the closure, it is also particularly preferred for a widened region to adjoin the through-passage opening, formed in the closure cap, towards the outside, and for the closure head of the closure membrane to be assigned to this widened region. For passing through the through-passage opening (as seen from the bottom upwards), the connecting wall can extend into the widened region. It is not absolutely necessary here for the connecting wall to rest against the widened region in the rest state of the closure. However, the connecting wall usually comes to butt against the widened region during a dispensing operation, this being accompanied by advantageous force conditions, which are described in more detail below, and by the opening operation in the closure head being influenced, usually assisted. Arranging the closure head, according to the invention, in the widened region results, first of all, in the closure head having a certain amount of support in the downwards direction, but, if appropriate, also in the radially lateral direction. In addition, the taper provided beneath the closure head by the widened region and the through-passage opening is advantageous in that it provides something of a positively locking seat for the closure membrane. Simple installation of the closure membrane is possible. Adhesive bonding or the like is not necessary. Nevertheless, the closure head has sufficient freedom of movement in order to carry out a discharge operation in an advantageous manner. The closure head itself may be comparatively thin. Nevertheless, the concave configuration and the radially inwardly acting support in the widened region produce a comparatively high closure force, which reliably makes it possible to achieve full closure of the discharge opening. This influencing or assisting of the closure force, and thus also of the opening characteristics of the closure membrane, may be provided on its own or in combination with the above-described influencing which can be achieved by turning the closure membrane inside out. Specifically, the closure head may be designed with slits which, starting from a center point, extend in the radial direction. In the rest state of the closure membrane, the slits are fully closed as a result of the slit-bounding sides pressing against one another. Upon actuation of the container on which such a closure is fitted, the closure head is forced outwards and opening is achieved by the slits gaping open. In combination with this, or as an alternative, it may be provided that the closure head has a permanent, central opening, a supporting plate, on which the closure head is seated in a sealing manner in the rest state, being formed beneath the opening, with the result that, in this embodiment too, full closure is achieved in the rest state. In a further detail, as regards said supporting plate, you are also referred to German Patent Application 19 51 0007, which is not a prior publication, and the international Patent Application PCT/EP95/01104. The disclosure of these earlier applications is included in the disclosure of the present application, also for the purpose of incorporating them in claims of the present application. In a further configuration, it is provided that a border bead, which projects beyond the closure head, is formed in an outer region of the closure head. Such a border bead, which nevertheless does not project beyond the through-passage opening in the rest state, is known in its own right, in a comparable closure membrane from EP-A2 545 678, which was mentioned in the introduction. In the context of the present invention, however, it is provided that the border bead is arranged in the area of the widened region, and thus outside the through-passage opening. Since the border bead is arranged in the area of the widened region, this means, at the same time, that this bead is turned outwards, and thus is exposed at the top. In addition, the bead is given support in the downward direction and radial support. This may be utilized, for the purposes of transportation safeguard, to provide a closure head or the like which acts on the border bead. Securing of the border bead not only obstructs an opening movement of the closure head to a certain extent, but also achieves, in particular, as a result of the flexibility of the material of the closure membrane, advantageous sealing in the transporting state. In addition, the sealing action is further enhanced by an increased internal pressure which may possibly arise during transportation if the container is subjected to corresponding pressure. It is also proposed that axe2x80x94furtherxe2x80x94widened region, which opens in the opposite direction, directly adjoins the through-passage opening, beneath the latter. One or both of the above-mentioned widened regions may be of essentially conical design. Overall, this produces something of a double rivet-like design of the inserted closure membrane and correspondingly advantageous retention of the closure membrane in the closure cap. In a further-preferred configuration, it is provided that a groove-like depression which reaches as far as the through-passage opening is formed in the widened region which adjoins the through-passage opening towards the outside. Specifically, the depression is preferably formed vertically and/or radially. This permits advantageous ventilation, for the sucking back of air into the container after a discharge operation. In this case, the air flows through a channel which is formed by the widened region and the through-passage opening and is covered by the connecting wall. It is also possible for corresponding air openings to be formed, as bores or channels, just in the wall of the widened region and of the through-passage opening. The air which has been newly sucked back results in a lifting action in the region of the border bead.
The invention is explained in more detail hereinbelow with reference to the attached drawing, which nevertheless merely illustrates some exemplary embodiments, in which: